A high quality growing medium, rich in naturally occurring trace elements for all pond, bog and marginal plants 4kg............£1.99 20kg..........£4.99

Any growing media for aquatic plants needs to be a heavy, almost a clay soil.
(A lighter soil would simply float away)
Turf is also a good growing media to line an aquatic planter with.
The grass binds the soil and stops it floating away.